Direct numerical simulation of a turbulent flow over an axisymmetric hill

Castagna, Jony; Yao, Yufeng; Yao, Jun

Abstract

Direct numerical simulation (DNS) of a turbulent flow over an axisymmetric hill has been carried out to study the three-dimensional flow separation and reattachment that occur on the lee-side of the geometry. The flow Reynolds number is Re H=6500, based on free-stream quantities and hill height (H). A synthetic inflow boundary condition, combined with a data feed-in method, has been used to generate the turbulent boundary layer approaching to the hill. The simulation has been run using a typical DNS resolution of δx + = 12.5, δz + = 6.5, and δy1+=1.0 and about 10 points in the viscous sublayer. It was found that a separation bubble exists at the foot of the wind-side of the hill and the incoming turbulent boundary layer flow undergoes re-laminarization process around the crest of the hill. These lead to a significant flow separation at the lee-side of the hill, where a very large primary separation bubble embedded with a smaller secondary separations have been captured. The present low-Re simulation reveals some flow features that are not observed by high-Re experiments, thus is useful for future experimental studies. © 2014 Elsevier Ltd.

• Journal Article Type: Article
• Acceptance Date: Feb 11, 2014
• Publication Date: May 22, 2014
• Deposit Date: Mar 10, 2016
• Publicly Available Date: Mar 10, 2016
• Journal: Computers and Fluids
• Print ISSN: 0045-7930
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 95
• Pages: 116-126
• DOI: https://doi.org/10.1016/j.compfluid.2014.02.014
• Keywords: turbulence simulation, 3D flow separation
• Public URL: https://uwe-repository.worktribe.com/output/817412
• Publisher URL: http://dx.doi.org/10.1016/j.compfluid.2014.02.014
• Contract Date: Mar 10, 2016